Its for 1990 Bmw 535I When i start my car the oil light comes on for like 2 sec but only sometimes. when i drive for a bit there is no light but when the engine warms up to half where it stays like that it starts to come on. When i stop my oil light blinks very fast and then it goes on solid red and the computer says "ENGINE OIL PRESS". When i accelerate or go to 1500 rpms the light goes off. when i stop it goes on again what can it be?

p.s i checked the oil level its good